Water irrigation sprinkler systems typically include a network of tubes or pipes a short distance below the surface of the ground to be watered, and a series of vertical risers or other connections extend upwardly to the surface of the ground where a sprinkler head is positioned. In many instances, such as for watering shrubs, a tubular riser extends well above ground to situate a sprinkler head at a desired location. Frequently, the sprinkler head or the riser is subjected to a blow that causes a break in the riser or its connections. Often this occurs when a sprinkler head is hit by a lawn mower or other equipment. On other occassions, a sprinkler head will become dislodged or stolen.
Whenever a failure in the riser or removal of a head occurs, the volume of water escaping at that location greatly increases due to the fact that the sprinkler head normally has a very restricted outlet whereas the riser or connection below it has a much larger cross-section. As a typical expample, a sprinkler nozzle operating at 30 psi may provide four gallons of water per minute. However, the flow through a one-half inch riser connected to the nozzle will, at that same pressure, provide about 30 gallons per minute with the sprinkler head removed. This results in flooding and a waste of water at that location.
At the same time, the increased flow at the high volume flow location causes a decrease in pressure applied to all the other sprinkler heads on that line, such that there is inadequate watering at those locations.
If a failure of this type goes undetected, the resulting loss of water is significant, as is the damage because of lack of water at the other locations on that line. With the high use of automatic sprinkler systems wherein the actual site being watered may be uninspected for long periods of time the loss can be greatly multiplied.
Flow restrictors have been known for many years to provide a relatively constant output flow with a relatively wide range of input pressures. Such devices are positioned in any location within a fluid system wherein uniform flow downstream from that location is desired. U.S. Pat. No. 4,105,050 illustrates one type of flow restrictor positioned immediately adjacent to a sprinkler head. If the sprinkler head is removed or broken away the flow does not increase in the manner outlined above since the flow restrictor prevents the increase. This is desirable from a standpoint of preventing water loss and maintenance of adequate pressures at other sprinkler heads in that same line. However, if the riser or the pipe below the sprinkler head should break, there is a resulting undesired water loss; and many, if not most, breaks occur near the joints at the ends of the riser, and particularly at the connection to the horizontal water input line.
Accordingly, a need exists for providing a system that will solve the problem outlined above, by minimizing water loss when disruptions in sprinkler systems occur.